Common Defects and their Remedy

Defects may appear in ice cream due to following reasons:

•  Use of low quality ingredients
•  Improper mixing of ingredients
•  Faulty method of manufacture
•  Faulty method of storage and transport

 Quality of ice cream is judged for its delicate and pleasing flavour, smooth body and texture and attractive colour. The reasons for the development of defects in ice cream and the preventive actions to be taken to remove the defects are discussed in the following paragraphs.

i. Colour and appearance Defects and Preventive Measures:

i) Un-natural colour in ice cream develop due to following reasons:

•  Careless-ness in adding colour
•  Improper use of colour
•  Use of foreign materials

 ii) Uneven colour results if the colour is not added and mixed properly.

iii) Excessive colour is due to addition of too much colour.

To avoid any of the above colour defects in ice cream correct amount of colour should be calculated, added and mixed thoroughly. Also the added colour should reflect the flavour characteristic of the ice cream. Cleanliness and neatness of the pakages should also be carefully observed.

ii. Melting quality defects and Preventive Measures

i) Curdy melt down or curdled melt down: It indicates high acidity in the ice cream mix or the effect of any other factor which causes instability of milk proteins. This defect makes the consumer feel that inferior quality materials were used in the preparation of ice cream. The defect may be corrected by:

•  Using fresh dairy products
•  Avoiding use of any product that might disturb natural salt balance of the mix
•  Avoiding freezing of high acid mixes

ii) Ice cream does not melt: Ice cream shows resistance to melting, retains shape when warmed and takes longer time to melt. The cause and remedial measures of the defect are discussed under soggy body defecs.

iii) Slow meltdown: It indicates use of excessive stabilizer (over stabilization) or faulty processing of the mix. This condition may be corrected by taking the following measures:

•  Reducing amount of stabilizer
•  Using fresh dairy products
•  Homogenizing the mix at proper temperature and pressure

iv) Whey leakage: When ice cream melts separation of whey occurs. This defect may occur due to poor quality of ice cream mix or improper balancing of mix. This defect can be corrected by:

•  Using good quality dairy products
•  Balancing the constituents carefully
•  Using better quality stabilizer

v) Foamy meltdown: This is caused by incorporation of too much air in the ice cream during freezing (excessive over run). Hence the defect may be corrected by reducing the over run and reducing the amount of emulsifier or egg products.

iii. Body and texture defects and Preventive Measures

The body of ice cream refers to firmness and consistency while texture refers to the fineness of the product, which is dependent upon the number, size, shape and arrangement of ice crystals and other particles. The ideal body of ice cream is that which is produced by the correct proportion of milk solids together with proper over run and which melts fairly rapidly at room temperature to a smooth liquid similar in consistency and appearance to sweet cream containing about 40 % fat.

i) Crumbly body: It is a condition in which ice cream does not hold together properly. It lacks cohesion or breaks apart very easily. It is associated with low total solids content, in-sufficient stabilization, excessive over run, imperfect homogenization and large air cells. This defect can be remedied by:

•  Increasing the total solids content
•  Increasing the stabilizer
•  Decreasing the over run

 ii) Soggy body: Ice cream with a dense body and wet appearance is an indication of soggy body. It is due to a low over run, high concentration of sugar that lowers the freezing point, excessive use of stabilizer or delayed packaging of ice cream after freezing. This defect is also similar to other defects such as gummy, doughy, sticky, pasty and gluey. Excessive stabilization or high total solids content produce a chewy or gummy body while certain types of gums and syrups cause pasty or sticky body. Soggy body and other related defects contribute to high melting resistance. These defects can be corrected by:

•  Maintaining correct over run
•  Reducing the quantity of stabilizer
•  Use of a combination of stabilizers
•  Reducing the sugar content

iii) Weak body: Ice cream lacks firmness or chewiness and is invariably accompanied by rapid melting. This defect is due to low total solids content combined with insufficient stabilization. This defect can be corrected by:

•  Increasing the total solids content
•  Adding correct amount of stabilizer
•  Properly ageing the mix

 iv) Texture of ice cream: Ice cream having an ideal texture will be very smooth,i.e., the solid particles too small to detect in mouth.

v) Buttery texture: This defect appears in ice cream when lumps of butter- fat are detected easily in the mouth. This defect is due to high fat content, inadequate homogenization, mix entering the freezer at a higher temperature and partial churning of cream due to slow freezing. This defect may be corrected by:

•  Homogenizing the mix properly
•  Ageing the mix properly
•  Freezing the mix quickly

 vi) Coarse or icy texture: When the ice crystals are large or not uniform in size or that the air cells are too large in ice cream, icy texture is indicated. This defect is most commonly noticed in retailer’s shop. Large ice crystal formation in ice cream may be due to

•  Insufficient stabilizer
•  Slow freezing in the freezer
•  Slow freezing in the hardening room
•  Insufficient ageing of mix

 Formation of large air cells may be due to:

•  Type of freezer used
•  Use of mix of low whipping ability

Sometimes small ice particles are found in ice cream. These ice particles are formed when water droplets get into ice cream. This defect may be eliminated by

•  Increasing total solids in the ice cream
•  Increasing or adding correct amount of stabilizer
•  Freezing quickly and drawing ice cream at a lower temperature from freezer
•  Hardening ice cream quickly
•  Reducing storage period
•  Avoiding frequent heat shocks to ice cream

 vii) Fluffy texture: This defect is due to presence of large amount of air cells. It is due to incorporation of an excessive amount of air either as large or small air cells. This defect may be expected when the total solids content in ice cream is not more than one third of over run. When the air cells are large and the amount of air is excessive the texture is sometimes described as snowy or flaky. This defect may be removed by

•  Decreasing over run
•  Increasing total solids
•  Decreasing the amount of emulsifiers

 viii) Sandy texture: This defect is easily detected by the presence of rough sand like particles in mouth when ice cream is tasted. This defect may be due to presence of more non-fat milk solids, which contribute more lactose. Higher amount of sugar may also lead to lactose crystallization. This defect can be eliminated by

•  Reducing milk solids not fat content
•  Replacing part of cane sugar with other sweetening agents like dextrose, corn syrup etc
•  Maintaining uniformly low temperature during hardening and storage.

iv. Flavour Defects and Preventive Measures:

Ice cream flavour is essentially a blend of flavours from different ingredients used in its preparation. The dairy products and flavouring materials used have profound effect on the delicate flavour characteristics of ice cream. Any defect in these materials will therefore influence significantly the flavour of ice cream.

Defects due to flavouring materials:

i) High flavour: Excess of flavouring material will impart a sharp bitter flavour in ice cream. Poor quality flavouring material also imparts bitter flavour. This can be corrected by checking the quality of flavouring materials and adding correct amount to get the desired delicate flavour.

ii) Low flavour: It is due to insufficient amount of flavouring material. It requires addition of correct amount of flavouring material to overcome the defect.

iii) Harsh flavour: It is due to use of inferior flavouring substances. These substances or artificial extracts lack fine flavour . Also use of excess flavor cause this defect. Therefore correct quantity of superior flavours should be used.

iv) Acid flavour: This is caused by the presence of excessive amount of lactic acid. This can be corrected by:

 Using fresh dairy products

 Prompt and efficient cooling of mix

 Avoiding prolonged storage of the mix at high storage temperature.

v) Bitter flavour: This defect may be caused by the use of inferior quality ingredients. The defect may be controlled by:

 Using good / fresh extracts

 Avoiding use of dairy products stored for long time at low temperature as

certain type of bacteria produce bitter flavour under these conditions.

vi) Cooked flavour: This is caused by over heating the mix or using over heated concentrated dairy products. The defect can be prevented by:

 Carefully controlling pasteurization temperature

 Using concentrated dairy products without cooked flavour

vii) Flat flavour: This results from the use of insufficient flavours, sugars or milksolids. By adding required quantities of various ingredients this defect can be corrected.

viii) Un-natural flavour: This is indicated by the flavour not typical of ice cream.The defect can be controlled by using good quality dairy products and flavouring materials.Synthetic flavours that are not correct imitation of true flavours are also considered un-natural. Similarly flavours due to poor gelation, fermented syrups,over-ripe or under-ripe fruits and rancid nuts are un-natural. Therefore use of such ingredients should be avoided to control this defect.

ix) Oxidized flavour: This defect is also known as tallowy or cardboard flavor and results from use of old or stored dairy ingredients especially fat rich products.This defect can be remedied by use of fresh dairy products and pasteurizing the mix at slightly higher temperature than recommended.

x) Shrinkage: Besides flavour and body texture defects one another defect is also noticed in ice cream, especially in retail shops. Sometimes when well-filled packages are hardened and stored, the volume of ice cream shrinks leaving space either at the top or on the sides of the package. Cups then do not appear full. This defect is known as Shrinkage defect. The main reason for this defect to occur appears to be excessive over run in ice cream and too much fluctuation in storage temperature. Maintaining constant temperature during storage and avoiding rough handling during transportation will prevent this defect to a greater extent in ice cream